Consumers of smoking articles are sensitive to a variety of characteristics that contribute to a pleasurable smoking experience, including among others the aroma of the smoking article itself, the aroma and flavor of the smoke generated by the smoking article upon ignition thereof, and the "mouthfeel" created by the smoke generated by the smoking article which has been inhaled. The term "mouthfeel" refers to the impact, body and other sensations (e.g., harshness, peppery, powdery, etc.) of the smoke produced upon ignition of the smoking article and inhalation of the smoke produced therefrom in the consumer's mouth.
A variety of tobacco flavorants have been used to adjust the characteristics of smoke generated by the ignition of tobacco products. See, e.g., U.S. Pat. Nos. 3,136,321; 3,316,919; 3,424,171; 4,421,126; and 4,506,682. Ideally, a smoking article will produce relatively little or no odor during its storage, but will deliver aromatic and flavorful smoke when ignited and will confer a subjectively pleasant mouthfeel when inhaled by the consumer.
Heretofore, investigators have isolated tobacco volatiles--characterized generally as having low molecular weights--and essences of whole tobacco extracts for use as tobacco flavorants. For example, published European patent application 326 370 by Fagg refers to a two-stage extraction process said to be capable of isolating tobacco essences. The process described refers to a water extraction method where a vessel housing an aqueous solution and a predetermined amount of tobacco is initially agitated and then spray-dried to form a dry powder. A second agitative extraction is performed on this spray-dried powder with a different solvent, such as methanol or ethanol, to yield a tobacco essence upon removal of the solvent. Published European patent application 269 545 by Grossman discloses a method said to be capable of extracting components from plant tissues useful as food supplements exhibiting antioxidant capabilities by a combined aqueous extraction and chromatographic fractionation process.
In recent years, it has also become increasingly desirable to produce smoking articles with decreased nicotine content. Although flavorless by itself, nicotine possesses the ability to enhance the contributions of the tobacco components responsible for providing the tobacco's unique aroma and flavor when the smoking article is ignited.
Previously, nicotine extraction processes have employed volatile organic solvents with and without alkaline agents. See, e.g., U.S. Pat. No. 1,949,012. One such process, described in U.S. Pat. No. 2,805,667, refers to an ion-exchange chromatography system which is reported to remove nicotine from an aqueous tobacco extract. The tobacco product obtained is said to contain less than 20% of its original nicotine content. However, this and other processes known in the art have been found to be disadvantageous because not only nicotine is removed from the tobacco but other components which characterize the tobacco's aroma and flavor are also removed, thus affording a substantially lower quality tobacco. In this regard, the foregoing processes for nicotine removal compromise the natural aroma and flavor of tobacco.
There exists a need for fractionated plant extracts, especially fractionated tobacco extracts that are essentially nicotine-free, and are useful as tobacco flavorants. In that regard, it would be desirable to develop a process for producing fractionated tobacco extracts which have nicotine selectively removed without eliminating or altering other tobacco components that are responsible for tobacco's distinctive aroma and flavor. It would also be desirable for these fractionated tobacco extracts to release that distinctive aroma and flavor only upon ignition of the smoking article or smoking substitute article to which they have been applied and to be non-volatile and remain substantially inert during manufacturing and storage.